Well yes, and no. The belt will only respond to what the engine, and cvt are doing. If the belt is worn too far it will not allow the cvt to work to its limits, there by reducing available output. It is important to measure it as shaka suggested. If there is a restriction in your set-up (intake/ exhaust) then even a good belt will only follow the "command" it is recieving. Same applies to an improper set-up in the cvt. (rollers/ springs/ worn parts). I would start w/ a through inspection of all the parts you want to run. This would include checking for wear limits on the clutch, belt, and drive surfaces. Once you are sure all is good you will have an easier time tunning. You may have a low compression situation, or perhaps a clogged muffler. Valve adjustment, worn rings, bad fuel filter, dirty air box, leaking vacuum line to the fuel supply petcock, or any one of a dozen more things. Try to systematically look the scoot over, and you will find the cause. Even low tire pressure will have a large effect.
